J B acceleration of fast ions in laser-target interactions

Abstract

By means of a two-dimensional computational model it is shown that under a non-uniform laser irradiation of a target, the J*B forces associated with grad n*grad T to T T spontaneously generated magnetic fields can produce fast ions with energy 10-100 keV. These originate from the low density plasma outside the critical density layer. By varying the parameters in the computational model, in particular the density gradient and the laser energy, the authors establish when this mechanism is more important than the ion acceleration produced from the hot spot which arises from magnetically reduced thermal conduction. This effect is likely to be more important with the occurrence of radiation induced density steepening.